(tex-font-lock-keywords): Make the pattern for

macros respect TeX's idea of identifiers.
(font-lock-set-defaults): Don't check for 'tex-mode, but instead
for 'plain-tex-mode, 'latex-mode, and 'slitex-mode which is what
tex-mode.el uses.

lisp/font-lock.el

@@ -634,7 +634,7 @@ This does a lot more highlighting.")
 
 (defvar tex-font-lock-keywords
   (list
-   '("\\(\\\\\\w+\\)" 1 font-lock-keyword-face t)
+   '("\\(\\\\\\([a-zA-Z@]+\\|.\\)\\)" 1 font-lock-keyword-face t)
    '("{\\\\em\\([^}]+\\)}" 1 font-lock-comment-face t)
    '("{\\\\bf\\([^}]+\\)}" 1 font-lock-keyword-face t)
    '("^[ \t\n]*\\\\def[\\\\@]\\(\\w+\\)" 1 font-lock-function-name-face t)
@@ -707,7 +707,9 @@ This does a lot more highlighting.")
 		  ((eq major-mode 'c++-c-mode)	    c-font-lock-keywords)
 		  ((eq major-mode 'c++-mode)	    c++-font-lock-keywords)
 		  ((eq major-mode 'perl-mode) 	    perl-font-lock-keywords)
-		  ((eq major-mode 'tex-mode)        tex-font-lock-keywords)
+		  ((eq major-mode 'plain-tex-mode)  tex-font-lock-keywords)
+		  ((eq major-mode 'latex-mode)      tex-font-lock-keywords)
+		  ((eq major-mode 'slitex-mode)     tex-font-lock-keywords)
 		  ((eq major-mode 'texinfo-mode)    texi-font-lock-keywords)
 		  ((eq major-mode 'shell-mode)      shell-font-lock-keywords)
 		  ((eq major-mode 'dired-mode)      dired-font-lock-keywords)